Centauro "C" 21 ft. Bandsaw, Verticle Set Up Quesitons

Den-Den · February 10, 2017, 08:08:42 PM

I have an old bandsaw with 30" wheels; so not as big as yours but it weighs close to 2000 lb. My blade speed is about 2500 ft/sec with a 5 hp motor. With that blade speed, 5 hp is more than adequate. I have been told that the blade speed is too slow but that has not been my experience. If I was doing serious ripping/resawing with power feed; I would probably increase the blade speed but not sure that a bigger motor would be needed for 6" pine.

Jnichols55 · February 10, 2017, 08:28:07 PM

Quote from: Den-Den on February 10, 2017, 08:08:42 PM
I have an old bandsaw with 30" wheels; so not as big as yours but it weighs close to 2000 lb. My blade speed is about 2500 ft/sec with a 5 hp motor. With that blade speed, 5 hp is more than adequate. I have been told that the blade speed is too slow but that has not been my experience. If I was doing serious ripping/resawing with power feed; I would probably increase the blade speed but not sure that a bigger motor would be needed for 6" pine.

Den Den, I think you mean "2500 ft. per min, not per second correct?

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Quote from: muggs on February 10, 2017, 07:32:32 PM
Yes resaws run faster than a normal bandsaw, so you can get a higher feed rate. I had a customer that wanted to buy a Northfield bandsaw. The factory told him it would not be a good idea since it was direct drive and turned too slow. If you regear the saw you may need that larger motor because you will getting less torque to the wheels. Muggs

But guys, and I guess I did not make it clear, a jack shaft has been added to this unit that is NOT stock. The original machines do not show a jack shaft, this was not built this way. The saw blade guys I have talked to say at least 4000 FPM for my machine. I guess all I'm saying is that I think it was not to add a bigger motor, but to get the FPM to the stock rate. Does that make sense?

thank you,
Jeff

Ljohnsaw · February 10, 2017, 08:35:54 PM

With your new blade speed calculation being about half of what is recommended, I'm guessing that the motor was replaced with what they had laying around. It probably had a 3450 speed motor from the factory...

Jnichols55 · February 10, 2017, 08:39:58 PM

John, I don't think so, I think the problem is the added jack shaft that geared everything down. I just check the specs on a 1989 model, that comes stock, 7.5 hp motor, just like mine, FPM spec is at 5,400. And this is direct drive, not jack shaft. So I'm thinking I should put it back to stock form. Leave the motor as speced, and see how it feeds. It has a pretty sharp Carbide tipped blade on it now. But like I said the FPM is about half of what it should be.

longtime lurker · February 10, 2017, 09:52:34 PM

Quote from: ozarkgem on February 10, 2017, 06:13:20 PM
curious as to why a bigger motor would cause more vibration. My 20 hp is as smooth as any of my smaller motors. I would think it would be smoother. The blade wouldn't slow as much and want to grab. Just my thinking. If it works with what you have use it.

Different critter.
An ST100 Stenner pulls a 4" band with 15Hp at about 6000fpm.
A McDonough E series pulls an 8" band with 75HP at 10000 FPM. Strain on that band is 12960 lbs.
I believe a Woodmizer runs around 4500 FPM at 2600 lbs pressure.

Not talking about the Centauro specifically bur most industrial band resaws run in the range of 6-8000 FPM. In terms of operating forces the OP,s resaw is closer to the Stenner then it is to your band mill.

I learnt something today... I been toying with trialing some Cooks or similar thin bands on my resaw. I now know that won't be happening.

Jnichols55 · February 10, 2017, 10:25:55 PM

Guys, I want to make sure I'm doing the math on this correctly. Here's the set up.

motor spins at 1750 RPM. the pully on that shaft is 4.5 inches , via a belt, that goes to a pully 10.5 inches, which is mounted on the jack shaft with a pully on the other end 4.5 inches, that then drives a 13" pully mounted to the lower wheel.

I've tried to attach a diagram, let's see if it turn out. Anyone want to see what the final RPM would be on the 13" driven wheel behind the lower bandsaw wheel? With 36" wheels, each revolution would equal 9.42 feet (36" x3.24 divided by 12")

I've been messing with this all day, my brain needs a reboot.
thank you,
Jeff

muggs · February 10, 2017, 10:59:10 PM

I can do ratio and proportion problems. But why.You can get a rpm meter off ebay quite cheap. then you know exactly what you have. Muggs

Ljohnsaw · February 10, 2017, 11:00:00 PM

Quote from: Jnichols55 on February 10, 2017, 10:25:55 PM
Guys, I want to make sure I'm doing the math on this correctly. Here's the set up.

motor spins at 1750 RPM. the pully on that shaft is 4.5 inches , via a belt, that goes to a pully 10.5 inches, which is mounted on the jack shaft with a pully on the other end 4.5 inches, that then drives a 13" pully mounted to the lower wheel.

I've tried to attach a diagram, let's see if it turn out. Anyone want to see what the final RPM would be on the 13" driven wheel behind the lower bandsaw wheel? With 36" wheels, each revolution would equal 9.42 feet (36" x3.14 divided by 12")

I've been messing with this all day, my brain needs a reboot.
thank you,
Jeff

I get 2,446.8 FPM on your blade. If you go from the 4.5" from the motor directly to the 13" you would have 5,706 FPM blade speed.

Jnichols55 · February 10, 2017, 11:00:48 PM

Trying my best to post pictures. I've created an album, I have the pix there, but for the life of me I can't figure out how to post them. When I click on "click here to add photos to post" it just returns me to my album and keeps adding the same pix there. Not to the post. What am I missing?????

What pitch (teeth per inch) do you have on the saw now?
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I'll second that. You said it came with used blades - they were probably waiting to get sharpened! Can you scratch your finger nail on the tip of a tooth (not running, of course! ;))? If not, sharpen or get a new one. ~~I'd~~ We'd like to see pictures!
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Jnichols55 · February 10, 2017, 11:04:17 PM

I get 2,446.8 FPM on your blade. If you go from the 4.5" from the motor directly to the 13" you would have 5,706 FPM blade speed.
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Bingo! John, same as I get. Thanks for double checking. For some reason someone added the jack shaft to cut the FPM in a bit more than half. So I'll will change it back to the way it was designed and go from there. Thank you for the confirmation!!

Jeff

Ljohnsaw · February 10, 2017, 11:05:36 PM

You start with being on the Forum and start (or reply to) a post. Then, hit the Forestry Forum Gallery in the left column. Back on the post, put your cursor where you want a picture to appear. Go to the Gallery window, select your picture and hit the Insert Into Post button.

Ljohnsaw · February 10, 2017, 11:07:13 PM

Quote from: Jnichols55 on February 10, 2017, 11:04:17 PM

I get 2,446.8 FPM on your blade. If you go from the 4.5" from the motor directly to the 13" you would have 5,706 FPM blade speed.

Bingo! John, same as I get. Thanks for double checking. For some reason someone added the jack shaft to cut the FPM in a bit more than half. So I'll will change it back to the way it was designed and go from there. Thank you for the confirmation!!

Jeff
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Your current blade speed is still pretty fast but maybe someone was trying to cut metal with it? ? ? Did you find any metal filings down inside the cover?

Jnichols55 · February 10, 2017, 11:14:32 PM

Quote from: ljohnsaw on February 10, 2017, 11:07:13 PM
Quote from: Jnichols55 on February 10, 2017, 11:04:17 PM

I get 2,446.8 FPM on your blade. If you go from the 4.5" from the motor directly to the 13" you would have 5,706 FPM blade speed.

Bingo! John, same as I get. Thanks for double checking. For some reason someone added the jack shaft to cut the FPM in a bit more than half. So I'll will change it back to the way it was designed and go from there. Thank you for the confirmation!!

Jeff

Your current blade speed is still pretty fast but maybe someone was trying to cut metal with it? ? ? Did you find any metal filings down inside the cover?
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No metal filings anywhere, just a lot of saw dust. I was told it had been used two owners back to slice veneer, or faces for guitars not sure which. A local college then bought it from the guitar guy, then another guy purchased it from the college but never set it up, I got it from him. So the history is murky to say the least. So I'm new to this, but half the normal FPM blade rate would not affect the lin. feed rate all the much? That sounds curious to me? Half as fast, or twice as fast on just about anything I owned from mini bikes as a kid, to everything else always seemed like a big difference. Not so in this case??

Jeff

Jnichols55 · February 10, 2017, 11:18:08 PM

Here's pic of the jack shaft set up that was added.

muggs · February 11, 2017, 10:16:57 AM

Somebody went to a lot of work to slow that saw down. My best guess is that saw started out life as a direct drive saw. The ones that I have seen, use 900 rpm motors[expensive] then the motor went bad. They didn't want to buy a new expensive motor. So they used what they had knowing it would be too fast. They just didn't do the math correct Muggs 8)

Jnichols55 · February 11, 2017, 10:28:16 AM

Quote from: muggs on February 11, 2017, 10:16:57 AM
Somebody went to a lot of work to slow that saw down. My best guess is that saw started out life as a direct drive saw. The ones that I have seen, use 900 rpm motors[expensive] then the motor went bad. They didn't want to buy a new expensive motor. So they used what they had knowing it would be too fast. They just didn't do the math correct Muggs 8)

Muggs, perhaps you are right, but the specs on the same models I've found both new and used, are 1750, and direct drive.

(EDIT: I take that back, upon closer look, you are correct 900 RPM, I was mixing "1750 with 7.50 hp!!

)

Who really knows the history of this machine, I sure don't. Any idea on how the increased speed will affect feed rate of stock? I'm hearing different opinions on that. One issue that Cooks expressed regarding feed rates was being able to clear the gullets appropriately (which results from faster feed rates) vs. them getting clogged and slowing everything down.

Jeff

Jnichols55 · February 11, 2017, 10:49:46 AM

I get 2,446.8 FPM on your blade. If you go from the 4.5" from the motor directly to the 13" you would have 5,706 FPM blade speed.
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John, So in light of all of this. The Cooks guy said I should target an FPM blade speed of close to 4500. Or should I go for the 5,706 FPM?

1. Do you concur with that target FPM?
2. With a 1750 Motor, I can't get that speed directly from the 1750 Motor to the wheel
3. But since I have the jack shaft set up. What pully changes do I need to make to get there?

I'm searching for a handy pully calculator that I can use to figure that out.

thank you,
Jeff

plowboyswr · February 11, 2017, 06:14:10 PM

If you'll look on the left hand side of the page just below the sponsors there is a red tool box. Click on it and it has all kinds of handy stuff in there including a pulley calculator and a band speed calculator. They are about 3/4 of the way down the list under the subhead Machinery. All you have to do is plug your info in. ;)

Kbeitz · February 11, 2017, 08:10:23 PM

This is one that I drew up many years ago...

Ljohnsaw · February 12, 2017, 02:13:26 PM

Quote from: Jnichols55 on February 11, 2017, 10:49:46 AM
John, So in light of all of this. The Cooks guy said I should target an FPM blade speed of close to 4500. Or should I go for the 5,706 FPM?

1. Do you concur with that target FPM?
2. With a 1750 Motor, I can't get that speed directly from the 1750 Motor to the wheel
3. But since I have the jack shaft set up. What pulley changes do I need to make to get there?

I'm searching for a handy pulley calculator that I can use to figure that out.

thank you,
Jeff

1. If that is what Cooks says, go for it. Having a faster blade speed means you either should push the wood through faster or risk dulling you blade because you are rubbing more than cutting. Significant? I don't think so.
2. Change the pulley size on the motor to a 3.5" That will get you just under the 4500 FPM with a 1750 motor (4438 fpm)
3. No need for the jack shaft.

Jnichols55 · February 12, 2017, 03:37:48 PM

[/quote]
1. If that is what Cooks says, go for it. Having a faster blade speed means you either should push the wood through faster or risk dulling you blade because you are rubbing more than cutting. Significant? I don't think so.
2. Change the pulley size on the motor to a 3.5" That will get you just under the 4500 FPM with a 1750 motor (4438 fpm)
3. No need for the jack shaft.
[/quote]

Thanks John, I'm going to swap that out this week, I'll give an update once I do that. Crazy how one (me) can go around and around on something like this, and realize your first few calcs were wrong and your make assumptions based on that. I'm eager to see how the increased FPM rate will affect things.

Jnichols55 · February 14, 2017, 12:42:52 AM

Well today I increased the speed on my 2" band saw and what a difference that made. Stayed with the same blade, a carbide tipped blade that appears to have never been used since it still had the felt tip markings from the saw shop. Hard for me to gauge just what the feed rate is now, I still have to tweak the belt power feeder actually replace the worn belt.

I was very happy with the feed rate and the quality of cut, consistency, etc. I feel a bit sheepish (nice word for dumb) in not being more careful at evaluating the actual FPM of the blade. Never assume your right when something seems wrong! It's running at about 4300 FPM vs. the 2500 it was at.

More experimentation and slight adjustments needed, but I'm on the right track now finally. Thanks for everyone's input. Now get back to your Mac Trucks, while I play around with this little 9' 2000 lb. light weight Pinto!

muggs · February 14, 2017, 10:41:59 AM

Good going. 8) Do you ever get up to Ft. Bragg? Muggs

Jnichols55 · February 14, 2017, 10:45:18 AM

Quote from: muggs on February 14, 2017, 10:41:59 AM
Good going. 8) Do you ever get up to Ft. Bragg? Muggs

Muggs I have not been up there is a long time, but why do you ask? Also, I grew up in Santa Paula, just over the hill from Camarillo! Small world

muggs · February 14, 2017, 12:46:12 PM

My friend Keven Drake moved up to Ft.Bragg to go to the woodworking school. When he found out he could not make a living building furniture. He started making fine hand woodworking tools. I trucked up several pieces of machinery to him. I also moved several people up there. Interesting town. I was in Santa paula a week ago heading up to Ojai. As you say small world. Have fun with your Pinto. :D Muggs